Post-quantum cryptography refers to cryptographic algorithms designed to resist attacks from both classical and quantum computers. Current blockchain cryptography, primarily elliptic curve digital signature algorithms, derives its security from mathematical problems that are hard for classical computers but potentially solvable for quantum computers. Post-quantum cryptographic schemes are built on different mathematical foundations, such as lattice-based problems, hash-based signatures, and code-based cryptography, that are believed to be resistant to known quantum algorithms including Shor's. The US National Institute of Standards and Technology finalized its first set of post-quantum cryptographic standards in 2024, providing a baseline that software and protocol developers can implement. The challenge for blockchain networks is not just implementing these algorithms but doing so in a way that is backward compatible with existing addresses, transaction formats, and smart contract infrastructure.